High-frequency radiator apparatus and resonator



A ril 8, 1952 w. w. HANSEN HIGH-FREQUENCY RADIATOR APPARATUS AND RESONATOR v Filed Jan. 6, 1943 3 Sheets-Sheet l FIG. 5.

Ill

n 1 1 n I I I I I l ENVENTOR WILLIAM W. HANSEN April 8, 1952 w. w. HANSEN 2,591,695

HIGH-FREQUENCY RADIATOR APPARATUS AND RESONATOR Filed Jan. a, 1945 s Sheets-Sheet 2 FIG.1'1.

ssQ- 45% PHASE AND AMPLITUDE 29 DJUSTMENT U H F FIG.

SOURCE i 34 1L- A FIG. 12. I

g MAGNETIC FIELD STRENGTH INVENTOR WILLIAM W. HANSEN ATTORN EY DISTANC April 8, 1952 w. w. HANSEN HIGH-FREQUENCY RADIATOR APPARATUS AND RESONATOR Filed Jan. 6, 1943 3 Sheets-Sheet 5 ill!!! e 1, i

ADJUSTABLE INVENTOR WILLIAM W. HANSEN FIG. 25.

Patented Apr. 8, 1952 UNITED STATES PATENT OFFICE Delaware Application January 6, 1943, Serial No.- 471,517

frequency electromagnetic wave energy having high directivity in elevation, uniform broad directivity in azimuth, and substantially horizontal polarization. This type of beam is especially useful for warning and like signal systems operated over seas, deserts, plains or like relatively flat surfacesof the earth, as it is desirable in systems so used to employ a stron horizontally polarized uniform beam generally parallel to the earths surface and having a wide continuous range in azimuth. Such systems do not of course require appreciable spread of the beam in elevation because of the very nature of their use, so that a large amount ofv energy can be concentrated in the azimuthal spread.

- Examples of preferred use of such systems are between ships on the ocean, between ships and shore, and between armored vehicles in the desert.

It is therefore a major object of my invention to provide a wave guide type antenna having novel arrangements for coupling it with a generator of ultra high frequency energy.

It is another object of my invention to provide ultra high frequency apparatus comprising the novel combination of cavity resonator means enclosing an oscillating electromagnetic field,v and The antenna associated antenna structure. structure proper may compriseany wave guide type antenna, such as an. open ended antenna horn, or a wave guide adapted to radiate wave energy through properly arranged apertures, suitably coupled to the hollow resonator.

tion or reception of directionalwaveenergy.

It is therefore also anobject of my invention to provide novel antenna and associated apparams for efficiently producing a reliable beam of electromagnetic wave energy having a,.relatively narrow spread in a given direction, uniform broad spread. in another given direction, and polarization substantially in the plane of the broad spread. For the above descr-ibed specific purposes, such a' beam has high-directivity in elevation, broad and uniform spread in azimuth andhorizontalpolarization.

The ap paratus may alternatively be used for the radia--- A- furtherobject of the invention is to provide ultra high fre uency apparatus wherein a hollow resonator of any suitable shape is adapted to be excited in a special mode of oscillation bearings; predetermined relation to the required directivity of associated antenna structure and the required polarization of the desired beam. Where therequired directivity and polarization are'horihon'tal, the lines of force of the oscillating electric field within the resonator are preferably horizontal. Where the resonator is a cylinder, the mode of excitation is preferably such that the oscillating electric field therein is everywhere paranel' to the cylinder ends.

A further object of the invention is to provide a novel associated antenna and hollow" resonator structure wherein an antenna horn is' directly mounted on and. coupled to be excited by the resonator.

A further object of the invention is to provide a novel associated antenna and hollow resonator structure wherein the antenna proper is an apertured hollow or dielectric filled wave guide. Preferably the resonator is coupled 'to excite a running wave along the guide.

It is afurther object of the invention to provide a novelwave guide antenna structure embodying special shape and/or dielectric arrangements for controllin the emitted beam shape.

A further object of the invention is to provide a novel wave guide antenna having. a tapered dielectric member therein.

A further object of the invention is to provide a novel Wave guide antenna having tapered walls.

and specially arranged energy emission apertures.

A further object of the invention is toprovide a novel Wave guide type antenna wherein battles are employed to controLdi-rectivity of the beam.-

Further objects of the inventionrwi-ll presently appear as the description proceeds in connection with the appended claims and: the annexed drawings wherein,

Fig. l is an axial section illustrating in some what exaggerated relative proportions a resonator and antenna horn structure according toa preferredembodiment of my invention;

Fig. 2 is a top plan View of the structure of sociated with Fig. 1, and illustrates the preferred",

mode of excitation of the resonator, andthe magnetic field gradient;

Fig. 5 isafragmentary sectional elevation showinganother manner of exciting. the resona-' tor of- Fig. 1;

Fig. 6 is a section along line 6--6 of Fig.

Fig. 7 is an axial section through the resonator of Fig. 1, and further illustrating optionally incorporated damper wires for eliminating all except the desired mode of oscillation;

Fig. 8 is a section along line 8-8 in Fig. '1;

Fig. 9 is a fragmentary elevation in section illustrating the structure of Fig. 1 provided with an antenna horn arranged at an'angle to the horizontal;

Fig. 10 is a somewhat diagrammatic .view illustrating a different shape of resonator which can be used in the type of assembly of Fig. 1, or in any of the embodiments of the invention.

Fig. 11 is a top plan view of a further resonator and antenna horn structure wherein theantennaextends over 180 as distinguished from 360 in Fig- 12 is a section along line [2- -4 2 in Fig. 11;

Fig. 13 is a top plan view of still further resonator and antenna horn structure wherein 180 spaced antenna horns having low azimuthal spread are employed;

Fig. 14 is a graphical illustration and comparison of the projected high frequency beams from the structures of Figs. 1, 11 and 13.

Fig. 15 is an elevation of an antenna structure similar to Fig. 1 but operating on a higher mode of oscillation;

Fig. 16 is associated with Fig. 15 and illustrates graphically one perferred location of the antenna horn coupling;

Fig. 1'? is an elevation, partly in section, of another embodiment of the invention wherein the resonator is coupled to a further form of wave guide type antenna through an axially located aperture;

1 Fig. 18 is a plan view along section line iS-i8 of Fig. 17.

Fig. 19 is a diagrammatic elevation representation of the optimum beam form emitted by the antenna of Fig. 17 for most purposes.

Fig. 20 is a diagrammatic elevatioanl representation of another beam form which may be produced by altering certain physical characteristics of the antennae of the invention.

Fig. 21 is an elevation partly in section of a variation of the antenna structure of Fig. 17, wherein energy absorbing means is provided on the antenna;

I Fig. ,22 is a somewhat diagrammatical view through a further embodiment of the invention, similar to Fig. 17 but having resonators on both ends of the antenna;

Fig. 23 is an axial section illustrating a further antenna variation for the structure of Fig. 1'7, wherein a tapered dielectric member is disposed within the antenna chamber;

Fig. 24 is an elevation partly in section showing a conical form of antenna chamber available for the structure of Fig. 17;

Fig. 25 is a front elevation of a further form of resonator and antenna structure provided with associated aperture and 'baiiie arrangements for obtaining and controlling the direction of radiated beam patterns.

- Fig. 26 is a side elevation, partly in section, of the structure of Fig. 25; and

f Fig. 27 is a section along line 2T2'| in Fig. 26.'

-R'eferring to Figs. 1, 2 and 3, a hollow metallic resonator cylinder H, which for the above-described preferred purposes is arranged with its axis 'A--A vertical, encloses a resonator space ii. A continuous circumferential slot 13 in the cylinder side wall It provides access to space I2. Since slot i3 is continuous and disposed at right angles to the axis AA, it effectively separates cylinder H into two distinct parts, but these parts are rigidly interconnected by spaced insulator posts i5 so that the whole structure is effectively maintained to define a cylinder. In this embodiment of the invention. the hollow radiating "wave guide type antenna comprises a continuous annular metallic antenna horn [6, which flares outwardly from a relatively narrow throat seated in slot l3 to an open mouth I! rigidly fastened to cylinder H. For most practical purposes the outer diameter of horn is may usually be considerably larger relativeto the diameter of cylinder ll than as shown in Fig. 1, so that it is to be remembered that the dimensions shown in Fig. 1 are somewhat exaggerated for purposes of illustration only and are not restrictive in any sense. The horn axis B-B, on opposite sides of which the horn walls taper substantially uniformly, is preferably disposed at right angles to axis AA and parallel to the surface of the earth or other planar surface over which a signal is to be projected. Line B-B also indicates a reference plane representing the signal direction in elevation.

Adjacent horn IS, a coaxial transmission line, comprising a hollow outer conductor l8 and an inner conductor wire 19, extends into a suitable aperture 23 in wall it. Conductor i8 is secured to wall l4, and wire 19 is reversely bent and secured to conductor 18. The reversely bent portion of wire [9 provides a loop 2| within space i2, which loop is arranged in a plane at right angles to the axis AA. The size of loop M is selected to obtain a proper impedance match between the transmission line and resonator II.

The purpose of the transmission line is to introduce ultra high frequency energy into resonator Ii magnetic field therein in a desired mode. By arranging loop 2! at right angles to the cylinder axis, I insure a mode of oscillation in space I! wherein the lines of electric force E are everywhere parallel to plane BB; that is, in planes parallel to the horizontal for the preferred purposes. The conducted current fiow on wall i4 within the resonator is in a plane perpendicular to axis AA and parallel to the plane of loop 2| as shown in Fig. 1. This particular mode of oscillation of resonator II will be hereinafter referred to as the circular E mode.

As shown in Fig. 4, the strongest magnetic field is adjacent the longitudinal axis of the resonator II, but it is not mechanically possible to couple the antenna horn at this region. For optimum practical results, I locate antenna horn H5 at the region where the accessible magnetic field is maximum according to Fig. 4, which is there half way along the cylinder wall. The horn'lfi and coupling slot l3 may be located at any other region along the cylinder wall to obtain different degrees of coupling.

j Energy introduced from the transmission line excites an oscillatingelectromagnetic field in the above-described circular E mode within space i2 with the lines of E in planes perpendicular to the resonator axis. This electromagnetic field loses energy through slot l3 into the antenna horn I-6 which is shaped to direct it as an annular beam of desired spread in selected directions. The distance across mouth I! determines the spread in one direction, vertical in the case for exciting an oscillating electrotaken. The circular E mode of excitation of resonator ll insures that the electromagnetic waves in the beam-broadcast by horn l6 are polarized horizontally which, as above explained, is desirable for most purposes of the invention.

The width of slot 13, parallel to axis A-A, must be chosen sufiiciently large that the radiation loss through slot I3 is large compared to the ohmic loss within the metal resonator II, for best efiiciency. Also the'width of slot I3 must beof optimum size for matching the impedance of horn [B to resonator II. It is further necessary during design to adjust the input coupling coefficient. of loop 2l with the resonator to correspond with the chosen size of output slot l3 when the. above considerations havebeen satisfied; The horn taper is preferably such that the emanating beam has a substantially planar transverse wave front.

Hence. I provide a- 360 spread horizontally polarized beam. of high frequency electromagnetic radiant energy, which, because of the horn shape, has high directivity in elevation. This beam is useful for the above-explained desirable purposes. While resonator II is shown as of cylindrical shape, it may be of any suitable shape in which the above-described circular E mode can beexcited. Thus itmay be aspherical, shell ll, asin- Fig. 10, or-may assume any of the other known equivalent shapes as will be apparent by reference to my earlier United States Patent No; 2,190,712..

Figszi and 6-illustrate a. further manner of exciting resonator II in the desired mode. 'A rectangularwave vguide22 is excited in a transverse. E modet-asshown, where the electric lines of force are parallel to the desired electric field direction irrthe:v resonator, here shown as horizontal. The. wave guide is rigid with cylinder wall. Hand coupled to the. resonator through a suitablexorifice 23 in wall I4. The size of orifice 23 is designed to provide a proper impedance match between the resonator and guide 22. By introducing the exciting energy in this manner, I' provide the same mode of oscillation in the resonator; as'gin Fig. 1.

Figs. 7 and, 8 illustrate a form of damper construction for insuring that the resonator is ex cited only in the. desired mode of oscillation. An upstanding conductor post 24. preferably on axis A-A, is rigid with the bottom wall of cylinder. ll. Three taut damper wires 25, each preferably of appreciable resistance, extend from the top: of, post 24. to spaced points on the periphery of that wall within the resonator. Wires 251 areso arranged that they areeverywhere at right angles. to the electric field of the mode of oscillation of Fig. 1, so that there are no currents induced in those wires by that field. However, any electric field corresponding to any othermode. of oscillation within the resonator I I will intersect wires 25 so as to induce currents therein, and the resistance of wires 25 is selected such: that the energy in any othermode. is entirely; dissipated therein. Wires 25 therefore dampen. all modes of oscillation. within the resonator ll except the desired circular E mode.

While I have illustrated plane 3-3 as hOlir zontal in Fig. 1, it will be appreciated that for certain purposes it may be desirable to produce a beam. everywhere directed at a slight angle to the horizontal. This may readily be done without appreciable, sacrifice of any energy or beam polarization by tilting the; antenna horn. as shown in Fig. 9 sothat its newdirection axislies in the conical surface of revolution indicated at B'B' which assumes an angle such as 0 with the horizontal. The beam shape in general is as shown in Fig. 19 in dotted lines. I havev discovered that tilting of the horn within reasonable limits does not interfere with the horizontal polarization of the beam, so that the other considerations in Fig. 1 need not be disturbed.

The azimuthal spread of the beam from the apparatus of the invention, shown as 360 in Fig. 1, may be made of any desired angular value. In Figs. 11 and 12, the beam spread is 180, horn 26 being only one-half the size of horn l6, and slot 2'! extends over only half the circumference of cylindrical wall 28 of resonator 29 corresponding to the position of horn 26.

Fig. 13 illustrates a further cylindrical resonator 30 wherein a pair of oppositely extending identical. horns 3| aremounted in suitable 180 spaced slots or orifices. (not shown) in the side wall of the cylindrical resonator. Horns 3| preferably have the same cross-section dimensions in elevation as horns l6 and 26, so as to have the same high directivity in elevation.

Figs. 1, l1 and 13 therefore illustrate the wide diversity of choice in azimuthal angular spread available under the invention. Fig. 14 illustrates graphically and in comparison the relative spreads and directivity of the difierent antenna arrangements. Circle 32 corresponds to Fig. 1, lobe 33 to Fig. 11, and lobes 34 to Fig. 13. Any other desired spread may be obtained by suitable antenna design.

In Fig. 15 the annular horn 35, which is preferably the'same as horn 16 in Fig. 1, is shown as located at one of the positions available'where the resonator is operated at a mode of oscillation higher than in Fig. l. Horn 35 may optionally be located at any position along the cylinder wall, but for maximum coupling it would be located at a maximum in the magnetic field along the Wall, as at B-B, CC and D-D.

For higher modes of oscillation it is often dif-.

ficult tomaintain efficient operation unless the high frequency source for the exciting transmission is of constant frequency, because a small change in frequency may shift the magnetic field relative to the throat of the antenna horn. Hence, excitation of the resonator in its lowest mode is preferred as in Fig. 1, but the arrangement of Fig. 15 can be employed if the source is frequency stabilized, or if its output frequency is controlled to maximize the excitation of the resonator.

In all of the above-described embodiments an antenna horn of selected shape is coupled directly to a suitable resonator by means of an energy transferring slot through which the resonator delivers electromagnetic wave energy to the horn, and all have substantially the same principles of operation as for Fig. 1.

.All of the above resonator or wave guide structures, or any individually as desired, may be filled with air, polystyrene or any other suitable dielectric material, for obtaining desired operational characteristics. It will be understood that when I refer anywhere herein to a resonator or waveguide or other space conductor, I intend to designate hollow conductor structure boundingaspace containing a dielectric which may be air or any such suitable material. 7

Figs. 17 and 18 illustrate a further embodiment of the invention wherein the wave guide type antenna. comprises a hollow cylindrical extensionof. the; resonator side wall apertured to losev radiant energy along its length. It will be 1111- derstood, however, that the resonator and antenna need not be of the same diameter, but may be of difierent diameters for obtaining desired characteristics.

Referring to Fig. 17, a hollow elongated right cylinder 36 of metal is separated by a transverse .partition 31 arranged at right angles to the cylinder axis A-A into a resonator space 38 and an antenna space 39. Wave guide 22, which is the same as shown in Figs. and 6, is excited in the same desired transverse E mode, here shown as horizontal, so as to produce in resonator space 38 the same circular E mode of excitation as above described for Fig. 1. .Any equivalent excitation for obtaining this mode of oscillation may be employed,

Except for its absolute dimensions, and the particular manner of'radiating energy to be described, the resonator defined by partition 3! and the lower end of cylinder 35 is similar in structure and mode of excitation to resonator H of Fig. 1. Further, as in Fig. 1, any resonator shape capable of excitation in the circular E mode may be used with antenna 36.

Central orifice 4! in partition 31 functions somewhat similarly to annular slot l3 of Fig. 1, in that the orifice launches energy from space 38 into the antenna space 39. The size of orifice 4| is chosen such that the energy loss into the antenna space is large compared to the ohmic loss within the resonator, and to match the impedances of the resonator and antenna.

The energy delivered from the resonator into the wave guide antenna sets up running waves inside the guide. A series of parallel circumferential rows of spaced circular apertures 42, 43, 44

and 45 are provided along the antenna side wall.

The distance parallel to axis A-A between each row is preferably substantially one wavelength of the running wave measured within the guide. Measurement of the wavelength within the guide is essential, as the wavelength in space outside the antenna may be diiierent than in the airfilled or dielectric filled guide. Any suitable number of rows, or spacing between the aper-' tures of the respective rows may be employed, according to the desired design. The diameter of holes 42- must be small compared to the wavelength in the antenna.

The axial length of antenna space 39 is preferably so correlated to the outlet aperture spacing and size that all of the energy is radiated from the antenna before the running wave reaches the upper end wall so that wall 46 could very well be omitted, if desired.

Fig. 19 illustrates in elevation the optimum form of the beam radiated by the antenna of Fig. 1'7. The radiations from the several rows of antenna outlet apertures mutually combine through known interference phenomena to produce an annular lobe which is substantially uniform over 360 in azimuth and has high directivity in elevation.

I can, however, alter the beam in both shape and direction by variation of certain physical conditions in the antenna. For example, for some antenna sizes, where the dielectric in the antenna is air, some of the energy may be devoted to formation of secondary lobes 41 which are much weaker than the main lobe 48 as shown in Fig. 20. If these secondary lobes are unwanted, the antenna may be filled with a high dielectric constant material, such as polystyrene, whereby the wavelength in space outside the guide is made mined row spacing.

substantially equal-to the wavelength inside the by the main lobe with the resonator axis may also be varied by varying the nature of thedielectric filling.

Similarly the direction of lobes 48 or 49,451

the formation or extinction of side lobes 4'1, may ;be controlled by varying the longitudinal spacing between the rows of outlet apertures 42-45. Equivalent eifectscan also be obtained by selected combinations of the above such as the combined use of a chosen dielectric filling and predeterapply to beams of smaller azimuthal spread. j.

I have also discoveredthat control equivalent to varying the outlet aperture row spacing may be effected by varying the frequency of excitation of the resonator. For example, it is possible to change the beam form from the annular horizontal shape 49 in solid lines in Fig. 19 to the generally conical envelope indicated in dotted lines in Fig. 19.

Since this variation in frequency may be controlled, as by any suitable automatic means-Ill for varying the resonator excitation, the devicemay be incorporated as an electronic scanning system wherein the beam sweeps back and forth between the solid and dotted line positions of Fig. 19.

Since the axis of the antenna of Fig. 17 is the same as the resonator, there is no alteration in the plane of polarization of the exchanged energy, so that the radiations in lobes 48 and 49 are horiaontally polarized in the illustrated position of the antenna, similarly to the beam obtainable from Fig. 1. Further explanation of the general principles of operation of the apertured wave guide type of antenna of Fig. 1'7, if necessary,

may be had by reference to my copending appli-' cation Serial No. 344,633, filed July 10, 1940, now Patent No. 2,489,288, of which the instant application is a continuation-in-part.

Where it is not practical or possible to radiate of stationary conducting wall 46, with an axially slidable wall 5| controlled by knob 52.

An energy absorbing block 53', which may between wall 51 and the top row of apertures 45.

. Any energy passing up the guide beyond apertures 45 is partially absorbed by block 53. Adjustable wall 5! reflects back any energy passingbeyond block 53 in such phase as to be completely absorbed thereby. When properly adjusted, wall 51 is located substantially one-quartor-wavelength from block 53. This arrangement substantially totally'dissipates any energy not radiated by the antenna.

Another arrangement which may be employed for the same general purpose is to locate a refi'ector on the bottom side of wall 48 as indicated at 54 in Fig. 1'7. In this embodiment also it is desirable to insure that the waves reflected back along the antenna wave guide are so phased as not to cancel the original waves, but to add to them.f Thus the reflected waves will lose energy alongthe antenna in the same manner as the original waves and will soon become dissipated.

It is possible to increase the output of the antenna if necessary by providinga duplicate The same considerations:

be of carbon or the like, is disposed across the guide.

resonator space 55 of identical construction with space 38 at the upper end of cylinder 36 as shown in. Fig. 22 for feeding the antenna. It is only essential to insure that the outputs of both resonators are so phased that the magnetic field maxima of the running waves derived from the respective resonators do not seriously oppose or cancel each other. This can be accomplished as by exciting both resonators from the same ultra high frequency source, and providing for phase and amplitude adjustment in the circuit leading to one of the resonators as shown in Fig. 22.

Fig. 23 illustrates a further form of the invention wherein the antenna encloses a solid tapered generally conical dielectric member 57 made of, for example, polystyrene, and which has its base secured to apartition 58 separating the resonator and antenna spaces. Partition 58 is centrally apertured to permit energy to be delivered from the resonator to the antenna.

The energy launched along the antenna from resonator space 38 is of continuually changing wavelength due to the nature of member 51. Hence, the spacing of the circumferential rows of outlet apertures 59 along the cylinder must be continually reduced to insure that a beam is emitted perpendicular to the axis.

Fig. 24 is a further variation of the hollow antenna structure of Fig. 17 approximately equivalent to Fig. 23. Here the antenna walls taper in substantially conical form from resonator 38, as indicated at 6!. The running wave traveling toward the apex of cone 6| is of constantly changing wavelength, and the spacing between aperture rows 62 is therefore reduced toward the apex to locate rows 62 in such spacing that a beam perpendicular to the cone axis is produced.

Other arrangements of dielectric members and dielectric fillings may be employed to obtain desired antenna radiation characteristics. For example, variations in the aperture row spacing, the antenna wall shape and the dielectric filling may produce various predetermined beam patterns. with or without secondary lobes, and describing annular or conical section patterns as desired. This may be obtained by combining any of the features of Figs. 1, 17, 23 and24.

Figs. 25-27 illustrate a further embodiment of the invention wherein the cylindrical antenna 36 has rows of outlet apertures 42-45 as in Fig. 1'7 but spread only over a hemicylindrical surface. A pair of diametrically aligned baille plates 63, 64 extend from opposite sides of the antenna. As indicated in Fig. 2'7, the distance from tip of 'each'baffi plate to the nearest outlet aperture, as measure along the baille and around the guide circumference, must be a wavelength or more.

Baffle plates 63 and 64 combine to limit the azimuthal beam spread substantially to 180. A beam spread of any desired azimuthal value can be obtained by suitable similar arrangements of baflie plates and apertures. The lower part of the cylinder in Fig. 25 comprises a resonator as in Fig. 1'7.

Obviously, the various forms of the invention may be employed for directive reception as well as transmission of wave energy.

While I have described the invention preferably for producing beams of horizontal polarization and direction, it will be appreciated that it is equally applicable for producing beams directed and polarized in other planes. This may be simply accomplished, for example, by locating axis A-A at any suitable angle so as to give axis B-B the desired direction.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In high frequency apparatus, a wave guide type antenna having means for producing a beam having a substantially circular spread in a selected plane, and means coupled to said antenna for feeding thereinto traveling electromagnetic waves having predetermined polarization corresponding to said selected plane said last-named means comprising means defining a hollow resonator directly coupled to said waveguide, and means for exciting said resonator in such mode of oscillation that the lines of force of the electric field therein are everywhere substantially parallel to said selected plane.

2. In high frequency apparatus, means defining a hollow resonato adapte to enclose an oscillating electromagnetic field, means for exciting said resonator in a circular E mode of oscillation, and antenna means directly coupled to said resonator for converting energy from said field into a high frequency radiant beam having a substantially uniform distribution in the plane of and a polarization substantially parallel to the electric field lines of said field.

3. In high frequency apparatus, means defining a hollow resonator, a wave guide type antenna, and means coupling said resonator and antenna for transmission of energy from one-to the other said antenna comprising a hollow conductive tube apertured along its length and periphery to permit escape of electromagnetic waves in accordance with a directivity characteristic which is substantially circular in a selected plane and highly directive in a plane normal to said selected plane.

4. In high frequency apparatus, means defining a hollow resonator having an apertured wall, means for exciting said resonator so as to set up a standing wave field therein having a predetermined mode of oscillation, and a hollow wave guide type antenna means coupled to said resonator adjacent said aperture so that energy from said field is launched through said aperture and along said antenna means said antenna means comprising a circumscribing omni-azimuth open mouthed antenna horn having its throat disposed at said aperture.

5. In highfrequency apparatus means defining a cylindrical resonator having an apertured wall, means for exciting waves in said resonator, and antenna means coupled 'tosaid resonator by said aperture so that axially symmetrical waves are launched therethrough and along said antenna means said aperture being located in a wall :parallel to the electric field within said resonator,

and said antenna means comprising a cylindrical conductor tube having a plurality of spaced parallel rows of outlet apertures.

6. In an electromagnetic wave radiator, an elongated hollow cylinder, an an axially apertured partition in said cylinder separating the cylinder into resonator and antenna chambers coupled through said aperture, said antenna chamber having apertures in th cylinder walls for broadside radiation.

'7. In ultra high frequency apparatus, means defined a hollow resonator, a wave guide antenna 11 coupled to said resonator, means for exciting and maintaining an oscillating electromagnetic field within said resonator, and means for damping oscillation within said resonator in substantially every mode except that corresponding to a predetermined mode correlated in predetermined radiation of said antenna.

8. In ultra high frequency apparatus, a hollow wave guide type antenna apertured along its length for the escape of energy, and means for launching running electromagnetic waves into said antenna at opposite ends thereof, said waves being maintainind in predetermined relative phase.

9. In ultra high frequency apparatus, a hollow tubular wave guide antenna, a dielectric member of longitudinally varying size within said antenna, and means for launching running electromagnetic waves along said antenna, the side wall of said antenna having apertures therealong axially spaced in predetermined relation to the charging wavelength of said waves as determined by the varying size of said dielectric member.

10. A hollow tubular antenna assembly of the wave guide type having a hollow resonator coupled to one end, an adjustabl reflecting wall across the other end, and energy absorbing means within the antenna adjacent said wall.

11. In a high frequency apparatus, a hollow resonator having an apertured end wall and adapted to enclose an oscillating electromagnetic field, means for exciting said resonator in a circular E mode of oscillation, a hollow wave guide type antenna means coupled to said resonator through said apertured end wall and in substantially axial alignment with said resonator for receiving therefrom a like circular E mode of oscillation, and means associated with said antenna means for radiating nergy from said field as a high frequency radiant beam directed in the plane of and polarized substantially parallel to the electric lines of said field.

12. In a high frequency apparatus, a hollow resonator having an apertured end wall and adapted to enclose an oscillating electromagnetic field, means for exciting said resonator in a circular E mode of oscillation, a hollow wave guide type antenna means having a plurality of axially spaced outlet apertures permitting the radiation of energy as a high frequency radiant beam characterized by a substantially uniform spread in a selected plane and a relatively high directivity in a plane perpendicular to said selected plane, said antenna means being coupled to said resonator through said apertured end wall and in substantially axial alignment with said resonator for receiving a like circular E mode of oscillation.

13. High frequency directional apparatus comprising means for 360 radiation in a predetermined plane of high frequency energy simultaneously from a plurality of wave guide apertures arranged in a linear array, said means ineluding resonant chamber means for producing equal phase delays between the radiation from adjacent equally spaced pairs of said radiation points, a source of high frequency ener y, and means for exciting said radiation means from said source whereby upon change in frequency of said source the directivity characteristic of said apparatus is correspondingly changed.

14. An antenna of the broadside wav guide type having a multi-apertured conductive surface shaped as a figure of revolution about an axis, and encompassing a uniform dielectric having a conical volume changing along said axis.

15 An antenna of the broadside hollow wave guide type having a multi-apertured conductive surface shaped as a figure of revolution about an axis and encompassing a uniform dielectric having a conical volume changing along said axis.

16. An antenna of the broadside hollow wave guide type having a inulti-apertured conductive surface shaped as a tapering conical figure of revolution about an axis encompassing a uniform dielectric.

17. In high frequency apparatus, means defining a hollow resonator, a wave guide type antenna, and means coupling said resonator and antenna for transmission of energy from one to the other, said antenna comprising a wave guide having a plurality of uniformly distributed apertures and being secured directly to said resonator at all points along its lower periphery.

WILLIAM W. HANSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,562,961 Heising Nov. 24, 1925 2,106,768 Southworth Feb. 1, 1938 2,106,771 Southworth Feb. 1, 1938 2,129,669 Bowen Sept. 13, 1938 2,129,711 Southworth Sept. 13, 1938 2,202,380 Hellman May 28, 1940 2,206,923 Southworth July 9, 1940 2,241,119 Dallenbach May 6, 1941 2,243,426 Kiroher May 27, 1941 2,245,669 'Hollman June 17, 1941 2,283,935 King May 26, 1942 2,304,540 Cassen Dec. 8, 1942 2,307,011 Barrow Jan. 5, 1943 2,407,690 Southworth Sept. 17, 1946 2,408,435 Mason Oct. 1, 1946 2,409,944 Loughren Oct. 22, 1946 2,461,005 Southworth Feb. 8, 1949 FOREIGN PATENTS Number Country Date 23,155 Australia June 22, 1936 114,368 Australia Dec. 9, 1941 507,473 Great Britain June 14, 1939 OTHER REFERENCES Proceedings of the I. R. E., vol. 26, No.12, December 1938, pages 1512, 1513 and 1514. 

